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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>自调用函数</title>
</head>

<body>
    <p>函数可以自动调用：</p>
    <p id="demo"></p>
    <script>
        (function () {
            document.getElementById("demo").innerHTML = "Hello! 我是自己调用的";
        })();
    </script>
</body>

</html>